The United Nations agency dealing with weather, climate and water says an El Niño event has begun in the tropical Pacific and is likely to continue into early 2010.
El Niño and La Niña bring significant temperature fluctuations in surface waters of the tropical belt of the Pacific Ocean: an El Niño event sees a rise in temperatures and La Niña witnesses a drop in normal temperatures.
These temperature changes are strongly linked to major climate fluctuations around the world, especially in Latin America, Australia and East Asia, which can last for a whole year or more. Both El Niño and La Niña can disrupt the normal weather patterns and have widespread impacts on climate in many parts of the world.
The UN World Meteorological Organization (WMO) said today that sea-surface temperatures in the eastern equatorial Pacific had risen to between 0.5 and 1 degree Celsius warmer than normal by the end of June, with similar temperatures in July.
“Scientific assessments of these observations indicate that this warming resembles the early stages of an El Niño event,” the Geneva-based agency stated in a news release.
“Although some of the atmospheric changes associated with this warming have been initially slow to develop into classical El Niño climate patterns, the warming is now well-established enough for scientists to conclude that it is consistent with a basin-wide El Niño event.”
In its most recent update on the subject, WMO stated that the expectation is for El Niño conditions to very likely prevail through the remainder of 2009 and into the first quarter of 2010.
“This expectation is based on model forecasts, and the typical life-cycle of El Niño events, which once established in the early-middle part of a year, usually persist through into the first quarter of the following year.”
The agency added that El Niño typically occurs once every four to five years, so the current assessments translate to a “substantially” elevated risk of an El Niño developing later this year.
At the same time, it noted that, in considering risk management strategies, it is important to keep in mind that many unusual climate patterns and significant climate extremes occur independently of El Niño.